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Old 11-22-2020, 02:41 PM   #21
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Originally Posted by nutdriver View Post
That is interesting that your 2019 came with gas charged shocks. I suppose it is possible that my 2018 Duramax 2500 did also but had already lost that gas charge. My original shocks felt very close to worthless in terms of compression and rebound resistance.
Gas charging in shocks is extremely common over the last few decades. The gas pressure in the shock keeps the hydraulic fluid from cavitating in the valves during high frequency cycling.

Quick way to check if a shock has lost it's gas charge is to remove, compress, then see if shock extends when released.

As for actual damping capabilities of an older shock, the valving is velocity dependent and once the piston/seal have seated in the pressure tube it's hard to test by hand. Most testing is done on a reciprocating device that cycles the shock more like it does under road conditions.

New shocks ALWAYS feel stiffer even though the old stocks are still functioning properly. The main difference is noticed in the "Butt-O-Meter" (to steal a term earlier used in this forum). Unless the shock has lost it's gas charge or is leaking oil, chances are it's still functioning.

Years ago some removed shocks from a major tire chain were tested by a Consumer Protection Group and it was determined that the only reason the shocks were bad was because their sales people said so.

They do wear out but not always as often as the "salesmen" say. Replace if you are having a problem but it's always a good idea to make sure the problem isn't caused by something else.
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Old 11-22-2020, 04:39 PM   #22
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Originally Posted by TitanMike View Post
Gas charging in shocks is extremely common over the last few decades. The gas pressure in the shock keeps the hydraulic fluid from cavitating in the valves during high frequency cycling.

Quick way to check if a shock has lost it's gas charge is to remove, compress, then see if shock extends when released.

As for actual damping capabilities of an older shock, the valving is velocity dependent and once the piston/seal have seated in the pressure tube it's hard to test by hand. Most testing is done on a reciprocating device that cycles the shock more like it does under road conditions.

New shocks ALWAYS feel stiffer even though the old stocks are still functioning properly. The main difference is noticed in the "Butt-O-Meter" (to steal a term earlier used in this forum). Unless the shock has lost it's gas charge or is leaking oil, chances are it's still functioning.

Years ago some removed shocks from a major tire chain were tested by a Consumer Protection Group and it was determined that the only reason the shocks were bad was because their sales people said so.

They do wear out but not always as often as the "salesmen" say. Replace if you are having a problem but it's always a good idea to make sure the problem isn't caused by something else.

No disagreements with anything you shared here. These are not the first shocks I have replaced. The shocks that I removed and still have do not extend after compression. After looking at several used Duramax shocks on Ebay, it appears that OEM shocks installed on Duramax are not pressurized. I am pleasantly surprised at the improved ride with the Bilstein 4600 and based on that the upgrade I feel it was a good investment.
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